A person who thinks that people want, or need to hear what they have to say, or what they think about any situation whether it directly involves, or has nothing to do with them at all. The majority of the time what they have to say is in fact ignorant bullshit, and the world would have been a better place if this person had not opened their mouth at all.

Kanye West Syndrome example 1:

The 'rapper' stormed the stage just after the first award, for Best Female Video was presented to Taylor Swift at the VMA's. He cut the teen singer off, grabbing the mic and protesting in support of Beyoncé.

"I'm sorry, but Beyoncé had one of the best videos of all time," he proclaimed as B looked on from the crowd, stunned. (This is the exact moment where Kanye West Syndrome is evident. What makes him think that his opinion is important or valued? It's the syndrome that makes him feel as though the mass of people gathered for this ceremony came to hear his opinion and appreciate him interrupting poor Taylor's acceptance speech.)